Legions of underground musical legends litter the heavy rock graveyard, and the list below surveys a horde of those rowdy rockers. All the bands covered reflect the Age of Aquarius rotting, with their twisted psychedelia or progressive rock, doom-laden or whirlwind riffing, or dissonant arrangements; and you can hear their echo throughout heavy metal’s many sub-genres today.

Some bands will no doubt be familiar and some, I hope, will be entirely new to your ears. Additional, and just as electrifying, ‘see also’ bands are listed here too, and while this list only touches upon the hard rocking scenes around the globe in the late ‘60s and early ‘70s, the aim here is to provide a primer to spark a proto-metal bonfire burning in your heart—or, if it’s already raging, to simply heap more fuel atop the inferno.

T2(1970, It’ll All Work Out in Boomland)

When you think of heavy metal’s forebears, it’s understandable your mind wanders to those wielding the meanest riffs first. However, progressive rock made just as much of an imprint on metal as hard rock ever did. British band T2 made a sterling contribution with 1970’s It’ll All Work Out in Boomland. The trio of vocalist/drummer Peter Dunton, bassist Bernard Jinks, and 17-year-old wunderkind guitarist Keith Cross released a single album before internal tensions split the original version of the band. It’ll All Work Out in Boomland is a fiery LP of stratospheric tunes, but it’s fueled by garage rock and scalding blues as much as meticulously sculpted prog. It’ll All Work Out in Boomland features highly-energized guitar work from Cross as he cuts through Dunton’s soaring harmonies with quick-flash bursts of darkness. The album is loose and groovy, and when all guns are blazing, fantastically intense. See also: Bodkin (Bodkin) and Zior (Zior).

High Tide(1969, Sea Shanties)

While heavy metal was getting into gear in the US in the late ‘60s, High Tide was on the verge of releasing a pre-metal UK masterwork with its debut Sea Shanties. The band was the musical birthing ground of violinist Simon House, who would go on to play with Hawkwind and David Bowie, among others, but vocalist and guitarist Tony Hill, bassist Peter Pavli and drummer Roger Hadden brought their share of weighty ideas and dexterous skills to the table too. The sizzling interplay between Hill’s guitar and House’s violin on Sea Shanties is pure genius, and Hill’s accomplished guitar work is some of the heaviest heard in the late ‘60s—see bruisers “Futilist’s Lament” and “Death Warmed Up”. High Tide never found more than a cult audience, and split after Sea Shanties‘s self-titled and more subdued follow-up. However, for one album, High Tide’s distorting riffs, doom-laden lyrics, and pounding percussion saw Herculean prog meld seamlessly with prim(evil) molten rock. Sea Shanties is, unequivocally, indisputably and irrefutably the best proto-metal album you’ve never heard. See also: Andromeda: (1969, Andromeda) and Haystacks Balboa (1970, Haystacks Balboa).

May Blitz(1970, May Blitz)

May Blitz’s self-titled 1970 album rests alongside Black Sabbath’s debut as a formative UK heavy rock classic. May Blitz wasn’t as heavy-footed as Black Sabbath, but what it lacked in mass was made up for in breadth. May Blitz featured an electric blend of doomy rock and sky-high, unhinged riffing, and while opening the album with the eight-minute-plus “Smoking the Day Away” was a bold gambit, the song puts all of May Blitz’s melodic and muscular accoutrements on full display. “Fire Queen” and “Squeet” are the heaviest and juiciest tracks—with drummer Tony Newman laying down driving beats for guitarist James Black to weave his phosphorescent riffs around. The band’s impressive second album, The 2nd of May was released quickly after its first, but the band dissolved soon after. Taken as a whole, May Blitz’s two albums show a vibrant awareness of a trio maximizing the possibilities (and volume) of their sound. See also Bakerloo (1969, Bakerloo) and Bulbous Creation (1970, You Won’t Remember Dying).

The Third Power(1970, Believe)

MC5 may have started kicking out the jams in 1969, but as the Third Power’s 1970 album Believe proved, there were plenty of other Detroit bands willing to join the rebellion. The trio might not have the status of MC5, and Believe hasn’t got the legendary presence of Kick Out the Jams, but the Third Power gave its all on debut. Singer and guitarist Drew Abbott, drummer Jim Craig, and bassist Jem Targal rip into psychedelically inclined hard rock tracks like “Gettin’ Together” and “Persecution”, while exhibiting plenty of nuance (and a little leftover hippie shake) on ballad “Lost in a Daydream”. The Third Power’s label, Vanguard Records, promptly dropped the band soon after Believe was released, citing various reasons, although it was clear they had no idea what to do with such a howling release. Label woes take nothing away from the fact that Believe is an exhilarating piece of work, and Abbott’s guitar histrionics sound invigorating to this day. See also: Lighting (1968-1971) and SRC (SRC).

Flower Travelling Band(1971, Satori)

If you combined the best elements of “Immigrant Song”, “In-A-Gadda-Da-Vida” and “Black Sabbath,” and then jumbled those up with Pärson Sound and Blue Öyster Cult, you’d have Flower Travelling Band—a group that sounds vaguely familiar, but wholly original. Formed by Yuya Uchida, the band went through a few different incarnations before settling in for 1971’s Satori. The album contains the five-part “Satori” suite, which journeys out to the edges of the universe on the trip to end all trips, before returning to earth to gaze at sacred bonfires. You’ll find piercing New York guitar lines, New Orleans blues, eccentric London rock, kaleidoscopic African, Middle Eastern and Southeast Asian chimes and smokin’ harp, pummeling percussion, and thrilling hard rock on the album. All is rolled, moistened, and smoked to its embers on Satori, and the 42-minute resulting masterpiece is one of the best heavy rock albums to have ever come out of Japan. See also: Taj Mahal Travellers (August 1974) and Far East Family Band (The Cave – Down to the Earth).

Craig Hayes is based in Aotearoa New Zealand, and he is a contributing editor and columnist at PopMatters. Alongside his reviews and feature articles, Craig's monthly column, RagnarĂ¶k, traverses the metal spectrum. He is the co-author of PopMatters' regular metal round-up, Mixtarum Metallum, contributes to radio shows and numerous other sites, and he favours music that clangs, bangs, crashes, or drones. Craig can be found losing followers daily on twitter @sixnoises.